As being a former official, I do not know, but this is such a judgement call and with the "new" stuff,it is going to be a mess. For years, it has been okay to hammer a kid on a crack back, as long as you do not hit him in the "numbers" on the back. Do I agree, nope, but the powers say that in order to be illegal, the player hit must fall to the ground on his face. Does it make sense? It just makes it easier to call (?) I really do not feel they will can it any different unless the head or above shoulders is involved. Good, bad, indifferent? Mi no sabe.